1. Field of the Invention
The present invention relates to a heat transfer recording sheet producing apparatus and a roll shaft supplying apparatus for producing a heat transfer recording sheet used in thermal facsimile devices and the like.
2. Related Background Art
Conventional facsimile devices use a heat transfer recording sheet in the form of a roll. This recording sheet is also called a donor, which has such a structure that a hot melt ink layer consisting of a binder of wax, resins, etc., and a color agent is laid on one surface of a thin, plastic film base, for example, of polyester. The ink layer of the recording sheet is overlaid on paper, and the back face of the recording sheet is heated by a heating means such as a thermal head to transfer ink to the paper, thereby effecting printing. Such facsimile devices are provided with an apparatus for indicating the end of the recording sheet.
For indication of the end of the recording sheet, an end mark with a reflective surface is normally provided in the vicinity of a fixed end (terminal end) of the recording sheet to a roll shaft. This end mark is given on either the hot melt ink layer side or the opposite side thereto of the recording sheet, and is optically detected by a sensor having a light source and a photodetector. This end mark is printed on the recording sheet by flexography or brushing.
However, in case of the end mark being printed by flexography where ink is deposited on the recording sheet using a rubber letterpress plate, the recording sheet would be conceivably crumpled during printing if it is thin.
On the other hand, in case of a small end mark being printed by brushing, there are problems that the quality of marking is poor and that the printing takes a long time.